Whenever talk about 4WD, most people will probably think of Audi. In fact, Jensen, a small British sports car maker, introduced the first modern 4WD system into its Jensen FF grand tourer as early as 1966.
Worked in collaboration with engineering consultant FF Development, Jensen's system employed the so-called "Feguson Formula" layout, that is, Viscous Coupling differential lock for both the center and rear differentials. This system is still the most popular 4WD system today. Accompany with the world's first anti-lock brake (though mechanical only), Jensen FF amazed the contemporary auto journalists by its superior stability.
However, without mass production, it was inevitably twice as expensive as a Jaguar E-type. Technical breakthrough it certainly had, but sales remained poor until production terminated in 1972.
Audi Quattro - successfully applied 4WD in mass production
In
1980, Audi unveiled a coupe based on the 80 sedan but equipped with a
4WD
system called Quattro. Technically speaking, this first generation
system
lagged behind Jensen's because it used manually lock-up center and rear
differentials instead of Jensen's LSD. Anyway, soon Audi upgraded
Quattro
to use Torsen center and rear LSD.
To establish reputation, Quattro appeared in World Rally Championship even before the road car delivered to customers. It immediately won the title in 1980 and continued dominating in the next two years. The road car also won appreciation about its handling from all over the world. The world-wide market for mass production 4WD road car started to take off as a result.
Golden period - 1983-1993
As Audi Quattro Sport succeeded in rallying, other major car makers also developed 4WD rally cars to compete in the Group B WRC rally. Since Group B cars were as powerful as 500 hp, 4WD must be superior than 2WD to handle so much power in the worst route. As a result, any participants should develop 4WD if they want to win. From 1983 to 1985, we saw many exotic 4WD rally cars appeared - Peugeot 205 T16, Lancia Delta S4, Ford RS200, Rover Metro 6R4 etc. This was one of the examples that motor racing accelerated the development of road car technology.
Group B rally was cancelled in 1986 as too many fatal accidents occurred. Instead, FIA established the less-powerful Group A that required a minimum production of 5,000 units and limited modifications. Such regulations led to more practical 4WD road cars developed, such as Lancia Delta Integrale, Ford Escort RS Cosworth, Toyota Celica GT4, Mitsubishi Lancer GSR and Subaru Impreza WRX.
In parallel to the rally car development, Audi started to put 4WD into every sedan models - 80, 90, 100 and 200, and all the subsequent models. The objective was to enhance active safety and security in wet / snow conditions rather than encourage fast cornering. Other contemporary sedans such as BMW 325 iX, Ford Sierra XR4x4, Peugeot 405 4x4 and all the non-turbo Subaru also followed this way.
On the other hand, 4WD also found opportunity in high performance versions of FWD cars because the combination of high power and FWD always result in excessive torque steering and tyre slip. Therefore they were upgraded to 4WD. Opel Calibra turbo, Alfa 155 Q4, Mitsubishi Galant VR4 and Renault 21 Quadra turbo belonged to this kind.
Depression - 1994-1999
Since 1994, more and more car makers stopped developping 4WD version of their new generation models. This was mainly due to the emergence of traction control and stability control. As I have mentioned, most sedans adopted 4WD to enhance wet / snow road safety, this also can be implemented by traction control and stability control. Since these electronic devices use ABS's hardware, they could be a lot cheaper than 4WD and have virtually no penalty to weight and fuel consumption.
In fact, 4WD is still superior because it really enhances cornering grip and cornering limit, while traction control and stability control just limit the engine output and apply braking to prevent the car from exceeding its traction limit. Therefore 4WD must corner faster and more stable.
However, this cannot justify for the high cost, so most major car makers dismissed 4WD. Here is a list of 4WD cars offering in 1992, in contrast to those offering in 1998. As you can see, Alfa, BMW, PSA, Lancia, Opel, Renault and Mazda completely stopped making 4WD cars, leaving Audi / VW and Subaru to be the only major 4WD makers, while Volvo is the only new participant in the past 5 years.
Year 2000 and Future - a revival ?
It seems that 4WD becomes popular again as SUV (Sport Utility Vehicle) and RV (Recreational Vehicle) take off. In America, nearly half of the new cars sold now are 4-wheel-drive SUV, although most of them actually employ old-fashion system without LSD. In Japan, nearly all new cars offer a 4WD version to choose from, and this also include the tiny K-cars !
Audi also sold most
of its
cars in America with Quattro installed, this led to the revival of 4WD
BMW 3-series in 2000. Will 4WD be revived ? Let's see.
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Audi A8, many people think it is unnecessary to use 4WD. In fact, A8 is the only 4WD car in its class. |